.....Using skin biopsies of young and old mice we demonstrated that advanced glycation end products (AGEs), such as argpyrimidine and pentosidine, accumulate in aged skin, whereas protein carbonylation is unchanged.
To investigate whether this discrepancy in accumulation is the result of an increased formation or due to reduced degradation we used modified collagen type I in in vitro experiments and tested for proteolytic susceptibility. We were able to show that collagenase is able to degrade oxidized and AGE-modified collagen. However, if collagen is cross-linked heavily, collagenase is unable to degrade the modified collagen. Cross-linking of collagen is preferentially taking place in collagen fibers treated with glycoxidizing agents
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